Migration to zero offset (MZO), alternatively known as the combined procedures of normal moveout and dip moveout (NMO/DMO), is a technique by which reflection data from a finite source and receiver offset is mapped to corresponding zero-offset traces. The MZO processes that are currently used are inadequate for a number of reasons. First, an inherent problem with current MZO processes is that they assume the source and the receiver are located in the same horizontal plane, called the acquisition plane. This assumption is almost invariably incorrect. Actually, the introduction of a rather small vertical source and receiver offset can introduce serious error in current MZO impulse responses. Furthermore, in ocean bottom seismic (OBS), or even land surveys with a deep borehole, there is a large vertical offset which is inherent to the survey. In these situations, assuming that the source and the receiver are in the same acquisition plane is simply not feasible.
Alternatively, to deal with a large vertical offset, current MZO processes shift the source and receiver to a common plane, called the datum plane. This is often called datumming or redatumming. Such conventional techniques result in a large amount of error and are extremely unreliable. Current techniques make this unreliable shift because they are without an acceptable and accurate alternative.
Thus, with the increasing importance of vertical cable and ocean bottom seismic (OBS) technologies, vertical offsets between the sources and receivers deployed in field acquisitions are significant, and must be formally accounted for in the MZO processes used in seismic processing.
There is a long felt need for a method of generating zero-offset traces from offset data, which does not shift the source and receiver to a common datum plane, and which does not presume a source-receiver pair in an acquisition plane. The present work fulfills this long felt need.